With an increased need for communication and information exchange, communication networks are becoming increasingly popular. Communication networks enable users to share resources and communicate among themselves. There are different types of communication networks, for example, wireless communication networks and computer networks. Some examples of wireless communication networks include Global System for Mobile Communication (GSM) networks, Time Division Multiple Access (TDMA) networks, Code Division Multiple Access (CDMA) networks, IEEE 802.16d (‘fixed WiMAX’) networks, and IEEE 802.16e (‘mobile WiMAX’) networks. A wireless communication network includes one or more base stations and one or more mobile devices. The wireless communication network covers a region that can be divided into cells. A base station is employed in each cell. A cell is an area in which the base station supports wireless communication between the one or more mobile devices. Some examples of mobile devices include mobile phones, Personal Digital Assistants (PDAs), laptop computers, and so forth. In wireless technologies, for example, in IEEE 802.16d and IEEE 802.16e, the uplink and downlink frames of each base station must be synchronized with other base stations to minimize co-channel interference. As a result, the base stations that are transmitting frames do not interfere with other base stations' frame reception from mobile devices in the network. The base station synchronization prevents collisions between the transmitted frames of base stations and the transmitted frames of mobile devices, and hence improves the throughput of the base station and increases network capacity.
In accordance with a known technique, base stations can be synchronized by using a Global Positioning System (GPS). A GPS receiver which provides a GPS timing reference is connected to each base station. The timing reference can be estimated from the signals received from the one or more GPS satellites. All base stations schedule their transmission events exactly at the same GPS time instant. However, the GPS receivers are expensive to produce, install, and maintain. Further, GPS signals are not always clear in all types of coverage areas, notably including dense urban areas, inside buildings, or underground. As a result, base stations located in such areas may not receive a very clear GPS signal. Consequently, the GPS receiver may fail to facilitate the timing signal in busy areas. Moreover, the failure of the GPS receiver can result in the failure of the timing in the base station.
Therefore, there exists a need for a method and apparatus that synchronizes transmission of frames by the base stations, without the need for external timing reference, such as, a Global Positioning System (GPS). Further, there exists a need for synchronization of the transmission of frames by base stations, with low production, installation and maintenance cost.